"I drop my kids off at school and walk down over the Heath to the café. If it opens at 10am, what am I going to do for an hour?"

Historian Dr Helen Fry

Dog walkers finishing early morning strolls on Hampstead Heath and mothers returning from the school-run were left reeling by news that the café would open an hour later each day under the new administration, meaning they would have to wait until 10am to get their morning coffee.

The Brewhouse Café is also a favourite haunt of local creatives – bestselling spy novelist John le Carré is often seen scribbling away at a table – and it was feared the move would stunt the creativity of musicians, academics and writers who work there.

But when contacted by the Ham&High, English Heritage, which manages Kenwood, insisted the rumours were unfounded.

It said that prestigious caterers Searcys is set to take over the running of the café, which is also frequented by Oscar-winning actress Emma Thompson, but would not change the opening hours.

Alex Sydney, head of English Heritage’s historic properties in London, said: “There are no plans to make any immediate changes and certainly no plans to change the opening times at the moment.

“I would like to reassure regular Brewhouse customers that both English Heritage and Searcys will work hard to ensure a smooth transition for everyone concerned.”

Historian Dr Helen Fry, who writes all her books in the café, was dismayed by the rumours.

“Everyone was outraged,” she said. “There’s a whole cluster of us who use it early. It would be devastating for us creatives. It’s a very literary, artistic space – it’s different from any other café.

“It has the quiet and the stillness that allows you to think about the project you’re working on. I drop my kids off at school and walk down over the Heath to the café. If it opens at 10am, what am I going to do for an hour?”

William Keegan, the Observer’s senior economics commentator, said: “I get all my ideas for columns and books in the café. I write my thoughts down on the back of the receipts they give you for coffee. It’s a tremendous routine!”

Jazz guitarist John Etheridge, who walks to the café most mornings from his home in South End Green, said: “There’s a lot of trade before 10am. I think it would be a rather foolish decision.

“We have a morning club of regulars who read the papers and have breakfast. I had breakfast with Doris Lessing up there and that was a breakfast to remember. Only in Hampstead could that happen!”

Searcys, which runs restaurants and bars at St Pancras International station, Blenheim Palace and the Barbican Centre, will take charge of the café from long-serving caterer Company of Cooks on October 1.

Following confirmation of the takeover, English Heritage published new opening hours on its website.

It is understood a member of English Heritage staff at Kenwood also confirmed to a regular customer that the café would open from 10am to 5pm under Searcys, rather than the current 9am to 6pm opening hours.

But an English Heritage spokesman insisted the changes to the website were a “human error” and would be amended.

Company of Cooks founder Mike Lucy said: “Of course I’m disappointed that our 18 years at Kenwood could not continue but as an independent business we simply were not prepared to match the financial bid from Searcys for the new contract.